Houston McCoy fired two blasts from his shotgun to bring down Whitman, who killed 16 people during nearly two hours of terror on the UT campus. Wayne Vincent, president of the Austin Police Association, said McCoy died Thursday in the rural West Texas town of Menard.

McCoy was 72 and had been battling a terminal illness for the past year.

Whitman wounded dozens of others before McCoy and fellow officer Ramiro Martinez made their way to the observation deck. Martinez also fired on Whitman.

Vincent called McCoy a good police officer who "answered the call" unsure whether he would live upon reaching the top of the tower.